Philco H-16 and H-26 field coils

[Ed Locker]

Hi All

Would anyone have the current ratings on Philco's H-16 and H-26 speaker field coils?

Thanks,
Ed

[Chuck Schwark]

Yes, I do. Will post the specs this evening when I get home from work.

[Chuck Schwark]

Ok,

Speaker Model H-16 (1933-35):

Field Coil D.C. resistance = 660 ohms @ 80 ma. max current
Voice Coil D.C. resisntance = 1.11 ohms (~ 3-4 ohm imp. speaker)

Speaker Model H-26 ( 1938 ):

Field Coil D.C. resistance = 460 ohms @ 60 ma. max current
Voice Coil D.C. resistane = 1.11 ohms (~ 3-4 ohm imp.)

The H-26 will not sub for an H-16 due to lower current max. and differnet voltage drop.

[Ed Locker]

Hi Chuck

I had a 37-650 follow me home a couple weeks ago. The original speaker(H-26) has it's cone destroyed.

I have a H-16 in good shape here. The game plan was to swap the output trannys and use the H-16, but with an extra 200 ohms introduced into the circuit, I dunno.

The thought of changing the field coil makes me ill.

Thanks,
Ed

[Chuck Schwark]

Ahhh....

The field coils, or "pots" as they're are called, may not be the same physically anyway. I would not try to swap, unless they are same diameter and core diameter dimensions.

I think the H-16 may be ok, since the A/C line voltage nowadays is higher than the 115 volts the 37-650 was rated at, the higher 120-125 volt A/C mains may compensate for the extra voltage drop on the field coil/choke that the H-16 introduces in the power supply. You cannot hurt the 650 with a lower B+ (due to field coil's higher resistance) , the set may still operate ok.

Give it a try. Worst case, the set may not pump out the audio wattage to shatter glass, but it may perform adequately with todays higher powered stations and still have the sensitivity to pull in all stations.

Keep us apprised of your "experiments."

Oooo.....rocket science with antique electronics....

Deja vu all over again......

[Ed Locker]

Well, I installed the H-16 and it works pretty well except for a annoying backround hum with the volume pot. at mininum. I've changed the polarity of the hum buck coil, the speaker voice coil and the polarity of the secondary of the output transformer.
I subbed the filters (59,59A and 57). I subbed resistor #58 with a 120 ohm-10 watt and a 22 ohm-5 watt and it still has this annoying backround hum. Tried different 6F6G's and the 5Y4G.
B+ is normal.

I am starting to beat my head against the wall. What in the world am I doing wrong? :

Thanks,
Ed

[Chuck Schwark]

Be sure the NEG sides of 59A and 57 are not to ground, but to the HV center-tap. This is also the NEG side of cap 59. The POS side of 59 goes to ground which filters the negative grid bias for the output tubes.

Note that in the schematic, cap 59 is drawn with the incorrect polarity and the POS terminal should go to ground.

[Ed Locker]

Yes, I noticed early on that cap. 59 was drawn backwards. It was replaced with a 10mf@25V axial, positive to ground, underneath the chassis. The HV CT is connected to the neg. of 59A and 57 then to resistor 58.

I'm about ready to start subbing parts that couldn't cause this, like the output tranny.

Thanks,
Ed

[Ed Locker]

Hi All

The 37-650 decided to start getting intermittent, RF gain would just nose-dive. This turned out to be a defective 6K7G IF tube.

After I replaced the tube, I was greeted with a pleasant bonus.....less hum! It still has just a little hum, which all my radios do. I'd call it normal.

The 6K7G was an original, that checked on the low side of "good" on my Jackson 648A. I figured it had a HK short, but I could only get the short indicator neon to flicker......with 7.5 VAC on the filament. No shorts with 6.3 applied.

Odd that an IF tube would increase hum with the volume control turned all the way down.

Ever heard of such a thing?

Thanks,
Ed